Effectiveness of increased salt iodine concentration on iodine status: trend analysis of cross-sectional national studies in Switzerland.
Andersson M., Hunziker S., Fingerhut R., Zimmermann MB., Herter-Aeberli I.
PURPOSE: Despite longstanding voluntary salt iodisation in Switzerland, data suggest inadequate iodine intake in vulnerable population groups. In response, the salt iodine concentration was increased from 20 to 25 mg/kg and we assessed the impact on iodine status. METHODS: We conducted a cross-sectional national study in school-age children (n = 731), women of reproductive age (n = 353) and pregnant women (n = 363). We measured urinary iodine concentration (UIC) and urinary sodium concentration (UNaC) in spot urine samples. The current median UIC was compared with national data from 1999, 2004 and 2009. We measured TSH, total T4 and thyroglobulin (Tg) on dried blood spot samples collected in women. RESULTS: The median UIC (bootstrapped 95% CI) was 137 µg/L (131, 143 µg/L) in school children, 88 µg/L (72, 103 µg/L) in women of reproductive age and 140 µg/L (124, 159 µg/L) in pregnant women. Compared to 2009, the median UIC increased modestly in school children (P